1. Technical Field
The present invention relates to impedance matching coupling elements, and more particularly, relates to the structure of an antenna having a matched input.
2. Description of the Related Art
A helical coil is known for capacitively coupling to a half-wavelength monopole radiator. A monopole radiator can be configured by providing a ground plane inside of a portable radio housing. U.S. Pat. Nos. 4,121,218 and 4,868,576 disclose examples of such antennas.
Although the above-described antennas are compact, the coupling of the helical coil to the antenna is lossy, thus consuming unnecessary energy. A lossy antenna structure decreases the battery life of a portable radio. In addition, these antennas also cause energy to be directed downward towards the portable housing. This energy causes induced currents to flow on metalized surfaces or shields of the radio housing which is energy inefficient and degrades the pattern performance of the antenna.